Computer-aided paint brush

[Nirav] painted this masterpiece by hand… with a little help from a computer. He calls it the semi-automatic paintbrush because you do need to move it over the canvas by hand, but a computer decides when to dispense the ink.

He’s using a piece of hardware we looked at back in September called the InkShield that got a boost from Kickstarter. It’s an Arduino shield that drives an inkjet printer cartridge. The trick is how to know when the cartridge is in position for printing.

The system uses visual processing for that. [Nirav] added an IR led to the cartridge, and uses a camera to extrapolate its position. He actually reused a Python homography module which he had written for use with a projector. That setup was developed as a digital white board, but works just as well for this purpose.

He mentions that results like this won’t be featured in an art museum. But the look is unique, and we’d love to make a set of geeky thank-you notes using the technique.

Actually, that is backwards. An optical sensor used in a mouse tracks relative movement, which means error would accumulate. This is using absolute tracking, meaning error does not accumulate.

The advantage to using the optical sensor though is that the Arduino can operate on its own without needing a computer to track the positioning. I was considering trying it out, and I may when I have time.

Nice. I had a similar idea years ago, envisioning a micro printer that I could use on the road to print received FAXs and such. Also, it would be used to print on objects that won’t pass through a regular printer, like T-shirts. Unfortunately, a Japanese inventor had already patented the idea. As for as I know, he never made use of his patent, which has likely expired by now.